Determining the crankshaft position is one of the main functions of electronic engine control. The injection of fuel, opening and closing of the inlet and outlet valves and, in the case of spark-ignition engines, the ignition for each cylinder are controlled as a function of the crankshaft angle in such a way that the individual working cycles are optimized.
Present approaches use incremental sensors on the crankshaft and/or the camshaft. Sensor disks having increment markings which, in conjunction with the signals, allow the engine position to be determined are widely used. German Patent Application No. DE 10020165 describes a method for detecting the rotational speed of an internal combustion engine, in which a sensor wheel is mounted on a rotating component. The sensor wheel includes a plurality of teeth which are scanned by the speed sensors assigned to the periphery of the sensor wheel.
One criterion for optimum engine start in automobiles is a start time which is as short as possible. It is achieved, among other things, by rapidly identifying the first suitable cylinder for fuel injection and ignition. Present engine controls need a certain rotational angle of the crankshaft for correct injection and ignition. This is due to the incremental sensors used, which are mounted on the crankshaft and the camshaft. Sensor disks having increment markings which, in conjunction with the signals, allow the engine position to be determined are widely used.
German Patent Application No. DE 19900641 describes a device and a method for detecting the rotational angle of the camshaft of a multicylinder internal combustion engine. To determine the camshaft angle, a permanent magnet and, next to it, a magnetic field-sensitive measuring recorder whose signal provides a control unit with a constant, high-resolution angle signal, are mounted on the camshaft. The advantage of the absolute angle sensor is the possibility of determining the crankshaft angle immediately after the control unit and the measuring recorder are turned on.
The disadvantages of the absolute angle sensors known from the related art include higher costs compared to the sensors for the increment system. Certain space requirements are often unable to be met due to the additional permanent magnet and measuring recorder, and additional signal processing must be implemented in the controller.
An object of the present invention is to achieve improved starting characteristics of an internal combustion engine having incremental sensors.